Exendin-(9,39) has been shown to have effects on beta-cell function, and after gastric bypass, to accelerate gastrointestinal transit. - infused at rates of 300pmol/kg/min. Given that gastrointestinal transit is typically delayed by Glucagon-Like Peptide-1 (GLP-1) and also that this hormone causes decreased food intake through increased satiation, it is reasonable to expect an effect of Exendin-9,39 on appetite. This may help explain the effects of gastric bypass on food intake. To examine the effect of Exendin on food intake we propose a dose-response study to determine whether the compound has effects in a dose-dependent fashion. We will examine the presence of gastrointestinal symptoms as well as food intake in the immediate aftermath of a test meal and the subsequent hours.

Inclusion Criteria:

• Subjects who have undergone Roux en-Y Gastric Bypass at least 6 months prior to enrollment in the study.
• Subjects without active systemic illness.

Exclusion Criteria:

• Subjects <20 years of age will not be studied to minimize the possibility of type 1 diabetes.
• Subjects >70 years of age will not be studied to minimize the potential confounding effects of age on glucose tolerance.